This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A176923 #9 Jun 11 2024 09:39:39 %S A176923 0,1,121,10201,12321,1002001,1234321,100020001,102030201,121242121, %T A176923 123454321,10000200001,10221412201,12102420121,12345654321, %U A176923 1000002000001,1002003002001,1020304030201,1022325232201,1210024200121,1212225222121,1232346432321,1234567654321,100000020000001,100220141022001 %N A176923 Squares of A057148 taken as decimal numbers. %C A176923 See comment in A057148. %o A176923 (Python) %o A176923 def A176923(n): %o A176923 if n == 1: return 0 %o A176923 a = 1<<n.bit_length()-2 %o A176923 s = bin(a|(n&a-1))[2:] %o A176923 return int(s+(s[::-1] if a&n else s[-2::-1]))**2 # _Chai Wah Wu_, Jun 10 2024 %Y A176923 Cf. A002779, A057148, A063009. %K A176923 base,easy,nonn %O A176923 1,3 %A A176923 _Jeremy Gardiner_, Apr 29 2010